1. Field of the Invention
The present invention relates to a method of manufacturing hexagonal ferrite magnetic particles and the hexagonal ferrite magnetic particles provided by the above method. More particularly, the present invention relates to a method of manufacturing hexagonal ferrite magnetic particles that makes it possible to obtain fine particles by inhibiting the aggregation of particles in the step of conversion to ferrite by calcination, and to the hexagonal ferrite magnetic particles that are provided by the above method.
The present invention further relates to a magnetic recording medium comprising a magnetic layer comprising the hexagonal ferrite magnetic particles obtained by the above manufacturing method.
2. Discussion of the Background
Hexagonal ferrite is employed in permanent magnets, and in recent years, has been employed as a magnetic material in magnetic recording media.
The method (coprecipitation method) of using calcination to convert into ferrite a coprecipitate obtained by coprecipitating an iron salt and an alkaline earth metal salt is a known method of manufacturing hexagonal ferrite (see Japanese Unexamined Patent Publication (KOKAI) Heisei No. 7-172839 and Japanese Unexamined Patent Publication (KOKAI) No. 2010-1171, which are expressly incorporated herein by reference in their entirety). The method of obtaining a coprecipitate by forming a reverse micelle (the reverse micelle method) has also been proposed as an improvement of the coprecipitation method (see Japanese Unexamined Patent Publication (KOKAI) No. 2007-91517).
Further, US2003/0077382A1, which is expressly incorporated herein by reference in its entirety, describes obtaining spherical ferrite particles by subjecting iron oxide or the like to adhering with barium or strontium carbonate followed by calcination.